1. Field of the Invention
The present invention relates to a cassette tape drive assembly.
2. Description of Related Art
Tape drive assemblies for cassette tapes contain a magnetic head which can write and read information by magnetizing and sensing the magnetic field of the tape. The information is typically stored in tracks that run parallel with the edges of the tape. The magnetic head is coupled to a stepper motor which can incrementally move the head from track to track. Information is read from the tape by moving the head to the appropriate track and sensing the magnetic field of the tape.
Cassette tapes are frequently used to store binary information from a computer and provide a backup storage device for the hard disk drive of the system. The advent of laptop computers has required backup tape systems to be both lightweight and small. Tape drive manufactures presently sell tape drive units that are 1 inch high (1 inch form factor). Commercially available one inch tape drives operate with tape that is 0.25 inches wide using a head that is approximately 0.52 inches high. To provide access to the full width of the magnetic tape the head must be capable of moving to the outer edges of the tape. The tape drive unit must therefore have enough space to allow the head to move the entire width of the tape. The tape drive must also have enough space to accommodate tolerances in the cassette tape and in the drive unit which houses the magnetic head. Conventional 1 inch drives must typically accommodate tape tolerances of .+-.0.030 inches. Additionally, the 1 inch high format has a tolerance of approximately .+-.0.020 inches, wherein the envelope for the drive unit may be as small as 0.98 inches.
There presently exist tape drives larger than 1 inch which utilize tape that is 0.315 inches (8 millimeters) wide with a head that is 0.64 inches high. Generally speaking, a 0.315 inch wide tape stores more information than a 0.25 inch tape. It would be desirable to provide a 0.315 inch tape in a one inch form factor using a conventional 0.64 inch high head with tolerances of .+-.0.050 inches (0.020 envelope tolerance +0.030 tape tolerance). Unfortunately the combination of a 0.64" head, a 0.315" tape and tolerances of .+-.0.050 (0.64+0.315+0.050=1.005) exceeds the 1 inch envelope of the one inch form factor.